test

Dieter and Jacco,

I inspected my three A-156 modules and A-155 this morning.

The A-155's Row 1 Pre Out was monitored using the DCV setting on hand-held DMM. Step 1 was held to output the maximum value, fully CW. With range set to 1V, I adjusted P9 until 1.000V on DMM. However, switching to 2V and 4V, the scale was still not wide enough. I chose to tune 4V to 4.000V which left 2V at 2.003V and 1V at 1.002 or so. A calibrated quantizer would correct this if necessary.

My method to test the A-156s was to use an A-176 CV Source to send 0.000V and +5.000V signals to an A-150 Dual VCS. The A-150 was toggled manually using a manual gate. T he output of the A-150 was verified using the DMM and sent to the CV Input of the A-156. The output of the A-156 upper or lower unit was now monitored by the DMM. Results varied.

Most units produced 0.000-0.0010V with the 0V at input and 4.972-4.983V with the 5V at input. Adjusting P4 only resulted in reaching 5.000V in one unit and that was at the maximum rotation of the trimmer. Most units only were adjustable to around 4.985V, and some of those started with a 0.002-0.010 offset. I attempted to adjust P1 but saw no change at the output. I must not understand the procedure.

Do either of you see a flaw in my test procedure Can I install a different size trimmer for P4 or a 1% resistor in place of R21 and improve the performance

Perhaps this should be moved to another thread, but one of the upper units has been unresponsive for ages and this calibration quest has prompted me to address it. The output is stuck at around 1.169 or 1.194V, it was different after turning power off and on. I thought perhaps it would be an issue with the CV In or Out socket itself, but prior to today wasn't sure of the offset or held voltage. Could the problem be Q1 or BU3 Is a voltage held indefinitely in the PIC or is it reset after power off

Thanks for your help!

Nick

On Friday, August 19, 2016, Jacco Ville jaccoville@... 1 < Doepfer_a100@yahoogroups.com > wrote:

..... Please take note that my approach of regulating is not the only way and so is my explaination ;-)

Hope you got the idea

Verstuurd vanaf mijn iPhone SE Lunatik

Op 19 aug. 2016 om 18:22 heeft Jacco Ville jaccoville@... 1 < Doepfer_a100@yahoogroups.com > het volgende geschreven:

I noticed some different behaviour of my A156's when testing my setup.

With a tuner on an A110 tuning from the A155 from C to C (seq knob fully ccw and cw) some came to C or B and when switching between 1V 2V and 4V it was not consistent.
So.... Time to make voltages visible.

Yesterday I finished fine tuning my four A156's and five A155's.

Once you know the drill it's not difficult, all it takes is some time and a precision voltage and measurement.

I used the A185-2 as a voltage source

and a Jones O'Tool Plus oscilloscope with a dual screen for voltage measurement in mV.

One input as source, the other from the A156.

As Dieter said, watch the offset.

Switch your precision adder between 0V and 4V.

I noticed there was a different quantizing sometimes (after regulating the P4 first!) when switching between 1V and 4V.

Then it made one step (note) to far (up). Then the P1 (cv1) or P2(cv2) comes in handy to regulate the threshold of the quantizer.

It acts as an attenuator, you can set quantizer steps earlier or later.

I made a list with calculated steps from 0,0833 to 1.000V and so it's easy to check where the threshold is for every step.

I used the attenuator from the 185-2 to walk through those steps and regulated that quantizing takes place at about 0,015V before the next step (note voltage) which leaves enough room for "minus offset" sequencer voltages.

Cheers

Good luck

Jacco Ville

Verstuurd vanaf mijn iPhone SE Lunatik

Op 19 aug. 2016 om 16:59 heeft Nicholas Keller maq163x2@... 1 < Doepfer_a100@yahoogroups.com > het volgende geschreven:

I hadn't thought to check the 156 for adjustment. I've been struggling with tuning for some time now and almost always have a 156 in the patch. Thanks for bringing this to my attention. I'll check the scale of my 155 while I'm at it!

On Thursday, August 18, 2016, Jacco Ville jaccoville@... 1 < Doepfer_a100@yahoogroups.com > wrote:

....And I certainly will do that.

Learning learning....

Funny thing, I am more collecting and adjusting my Doepfer setup (or Dieter room as my wife is calling it) then making sounds.

But I think it is the best way to know the working of every part of this system.

Cheers

Jacco Ville

Verstuurd vanaf mijn iPhone SE Lunatik

Op 18 aug. 2016 om 12:19 heeft yahoo@... 1 < Doepfer_a100@yahoogroups.com > het volgende geschreven:

> .... By the way ;-)
>
> I found out the attenuator function of P1 and P2
> Very handy to set the threshold of the quantizer behaviour.
> I noticed that with critical voltages from my A155's with a knob
> fully cw the voltage of 0.970V in 1V modus was not enough to get
> a full scale from C to C.
> Now I made the threshold of the A156 a few mV earlier to deal with
> this problem.
>
> Cheers
>
> Jacco Ville
> The Netherlands

That's a solution. But the correct way would be to adjust the A-155 so that
it outputs 1.0V in 1V mode. For this a trimming potentiometer (P9') is
available on the upper A-155 potentiometer board.

Best wishes
Dieter Doepfer

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27139 Re: 1 Tuning references for A156 quantizer